Call-distributing system



Jun s 1926.

1,587,515 G. R. EATON CALL DISTRIBUTING SYSTEM Filed April 14. 1920 3 Sheets-Sheet 1 oeaao'ooo kw "(5L s km 11.1%.. Lil mLgL June 8 1926.

1,587,515 G. R. EATON CALL DISTRIBUTING SYSTEM Filed April 14 1920 3 Sheets-Sheet 2 June a 1926. I 1,587,515

I G. R. EATON CALL DI STRIBUTING SYSTEM Filed April 14. 1920 3 Sheets-Sheet 3 Q1 [Hz/272.47? V Patented .llune d, 1926,

onene s n. nron, or can rrinir, rnnrno IS, ASEIG-NOE T0 KELLQGG SWITCHBOARD AND SUPPLY COMPAJHY', 01" CHICAG-Q, ILLINOIS, A GORIEOBATIQN OF ILLINOIS.

A SCQ BU IW Y$TE1L Application filed April 14, 1920.

My invention relates to telephone systems in which link or trunk circuits are employed for interconnecting telephone lines and has to do more particularly with that type of telephone system employing both manual and automatic apparatus.

An object of my invention is to provide an improved distribution and circuit arrangement for inczeasing the speed otconncctinp; lines to trunks when finder switches are used to connect trunk circuits to calling lines.

Another object of my invention is to decrease the average number of steps a finder switch has to travel in connecting a calling subscribers line to a connecting link or trunk circuit.

1 preferably divide the subscribers lines into groups of fifty and associate with each group of fifty lines six finder switches, any one of which may be started when a call is initiated to select back and connect to a calling subscribers line. 01? course, I can increase the capacity of the finder switches to one hundred or any desired number hank contacts and provide as many finder switches for a group of lines as I find necessary and desirable to handle the ti'afiic.

With the oldmethod of multipling the subscribers, lines are multipled straight throui rh the bank contacts oi the difierent finder switches, and only one master switch is provided, wich starts one finder switch aiter the other as the calls come in. With this method of connecting the subscribers? lines to. the finder switch banks, it isobvious that it takes a longer time for the finder switch to connect to a subscribers line that is con- 1 nected to one of the last sets of contacts in the bank of contacts than it does for the finder switch to connect to a subscribers line which is connected to one of: the first sets or? contacts in the bankot contacts. It oitten occurs that when a subscriber whose line appears in one of the last sets of conl'acts in the finder switch banks initiates a a call, and before the started finder switch vbar-i.rotated far enough to connect to .the call? line, a second calling subscriber initi a cal whose line appears ahead of the first calling-g line in the bank of contacts; coir Serial No. 373,843.

sequently, the started finder switch connects to the second calling line and the first calling line has to wait until the master switch starts a second finder switch. In. a straight multiple system 01" this kind the first subscribers of a group of subscribers will receive preference for the reasons above described, and to overcome this objectionable feature, one of the features of my invention is the provision of means whereby the bank multipie of the switches are slipped by smaller glOUPS between the difierent finder switches of a group of finder switches.

Each group of fifty lines is further divided into five sub-groups of ten lines each, and the first ten lines in the first finder switch Jill occupy the first ten contact sets; in, the bank of the second finder switch they will occupy contact sets 11 to 20, inclusive, and in the bank ofthe third finder switches they will occupy contact sets21to 30, inclusive, etc, as will. be more fully hereinafter described.

I also arrange the finder switches so that whens subscriber initiates a call in the first sub-group of subscribers lines, the first finder switchof the group is started; and when a subscriber initiates a call whose line appears in the second. sub-group of subscribers lines in the first finder switch the second finder, switch of the group is started in whose bank the second sub-group of lines appear as the first sub-group of contacts so that the second finder switch only has to search through its first sub-group of contacts to find the calling line, etc, for the other sub-groups of lines.

It a call is initiated in the first sub-. group of contacts, that is, in sub-group of lines nun'ibered 1 to 10, the first finder switch rill start and find the subscribers line in its first sub-group or" contacts. Now, it a second call is initiate in the same group, the sixth finder switch is started and will find the subscribefis line in. its first-sub group of contacts.v If a third call initiated inrthe same group, the fifth finder switch is started, and it will find the line in its second sub oufp, or contacts, etc. It five calls should be initiated at once, one in each subgroup of lines, the first five finder switches will be started and each finder switch will find the call initiated in its sub-group in its first sub-group 01' contacts.

The above features, as well as others, will be more particularly pointed out in the ensuing specification and in the appended claims.

Reterrnig now to the accompanying drawings,

Fig. 1 illustrates diagrammatically a group of six finder switches associated with a group of fifty lines and illustrating the manner of slipping the bank contacts;

Fig. 2 illustrates a skeleton arrangement of the line circuits and finder switches, showing the master starting conductor and its association with the finder switches;

Fig. 3, Part 1, illustrates diagramn'iatically a calling substation in association with a tinder switch which terminates in a set of jacks and lamps; and

Fig. 3, Part 2, diagrammatically illustrates a cord circuit for extending a connection from a calling substation to a called substation.

Referring now to Fig. 1, I represent diagrammatically siX fifty-point finder switches FS, FS, FS F55 F8 FS, and I illustrate the lines preferably in a fiftyline group slipped in sub-groups of ten lines each. Lines 1 to 10 appear as group a (bank contact sets 1 to 10, inclusive) in the bank of switch FS; appear as group a (bank contact sets 1 to 10, inclusive) in the bank of finder switch F8 appear as group a (bank contact sets 11 to 20, inclusive) in the bank of switch FS"; appear as group a (bank contact sets 21 to 30, inclusive) in the bank of switch F as group or (bank contact sets 31 to 10, inclusive) in the bank of finder switch F8 and appear as group a (bank contact sets 41 to 50, inclusive) in the bank of finder switch FS.

Lines 11 to 20 appear as group 7) (bank contact sets 1 to 10, inclusive) in the bank of switch FS; appear as group 7) (bank contact sets 11 to 20, inclusive) in the bank of switch FS; appear as group (bank contact sets 11 to 20, inclusive) in the bank of switch FS"; appear as group (bank contact sets 21 to 30, inclusive) in the bank of switch F8 appear as group 5 (bank contact sets 81 to 40, inclusive) in the bank of switch F5 and appear as group 72 (bank contact sets 41 to 50, inclusive) in the bank of switch FS Lines 21 to 30 appear as group a (bank contact sets 1 to 10 inclusive) in the bank of switch FS appear as group 0 (bank contact sets 11 to 20, inclusive) in the bank of switch FS; appear as group 0 (bank contact sets 21 to 30, inclusive) in the bank of switch FS; appear as group 0 (bank contact sets 21 to 30, inclusive) in the bank of switch FS'; appear as group 0 (bank contact sets 31 to 10, inclusive) in the bank of switch F5 and as group 6' (bank contact sets L1 to 50, inclusive) in the bank of switch FS Lines 31 to 10 appear as group (Z (bank contact sets 1 to 10, inclusive) in the bank of switch FS appear as group (2 (bank contact sets 11 to 20, inclusive) in the bank of switch FS"; appear as group (Z (bank w contact sets 21 to 30, inclusive) in the bank of switch FS; appear as group (Z (bank contact sets 31 to 40, inclusive) in the bank of switch FS; appear as group (Z (bank contact sets 31 to 40, inclusive) in the bank of switch FS; and appear as (Z (bank contact sets 4-1 to 50, inclusive) in the bank of switch F5 Lines 11 to 50 appear as group 0 (bank contact sets 1 to 10, inclusive) in the bank of switch F8 appear as group (2 (bank contact sets 11 to 20, inclusive) in the bank of the switch FS; appear as group a (bank contact sets 21 to 30, inclusive) in. the bank of switch F8 appear as 0 (bank contact sets 31. to 10, inclusive) in the bank of group FS; appear as group 0 (bank contact sets 41 to 50, inclusive) in the bank of switch FS; and appear as group 0 (bank contact sets 41 to 50, inclusive) in the bank of switch FS.

Referring now to Fig. 2, I illustrate diagrammatically five groups of ten lines each as a, b, a, (Z and e of a group of fifty lines. The three contacts of group a are strapped together and represent a group of ten. line relays associated with the group of lines 1 to 10; group 6 represents a group of ten line relays associated with the group of lines .11 to group 0 represents a group 01 ten line relays associated with the group of lines 21 to group (Z represents a group of ten line relays associated with the group of lines 31 to group (2 represents a group of ten line relays associated with the group of lines 11 to 50. The switches F5, F3, FS FS, F and F8 are shown associated with their associated groups of lines a, 7), e, (Z and e. The method for starting the different switches as the calls are initiated by the subscribers in the different groups of: lines, will be more fully hereinafter described.

Reterring now in general to the circuit arrangement as illustrated in Fig. 3, 1 and 2, it illustrates the mechanism and the apparatus necessary to connect the calling substation A to called substation C. The calling substation A is of the well-l-znowu common battery type, connected by line limbs to the central ofiice link circuit L, which includes a line relay LR, cut-oil relay Ct), together with multiple jacks J and the mul tiple bank contacts 6, 7, 8 and 9 of the finder switches as each subscribers line appears in P a rts means of a ratchet and the hanks of di ierent tinder switches, as

already described. The lintler switch 1 3 ent posit-ions on the switchboard as it is found desirable to multiple the lamps LL and jacks AJ to secure an adequate traiiic distribution. The tinderswitch FS may he of any desired and si'litalcle construction and is provided with a springu'estored switch shaft and wipers 2, 3, l and 5 and with four sets of bank contacts 6, 7, Sand 9 ofiitty contacts-each, to which the fifty subscribers lines are connector. A rotary step by-step magnet RM is provided for rotating the switch shaft and wipers 2, 3, 41: and 5 by i awl mechanism. Sets oil hank contacts (5, 7, 8 and 9 and a retaining pawl are also provided and adapted to be operated by the release magnet RE for permitting the switch sha l t and wipers 2, 3, t and 5 to restore to normal by springs tension. lhe starting conductor SWV is a common starting wire and is connected to a contact of each cit-the linerelays LR of the group of 'Slll scrihers which is associated with the finder switch FS. A sleeve cut-oil relay S00 is adapted upon energization to connect the finder switch wipers 3, 4t, and 5 through to the multiple jacks AJ. The

starting relay extends the starting con ductor EllV through to the next finder switch ,FS (not shown) when the switch FS is taken for use. The finder switch FS also includes a double-woundtest relay TR, a line relay l1 and a set ofoll-normal contacts ON.

lhecord circuit E comprises an answering plug Al and a calling plug UP, "the said'answering plug A1 and calling plugCP heing connected by the heavily marked conductors and having the condensers 12 and 13 interposed. Associated with'the answering end of the cord circ it E is an answering sleeve supervisory relay AS and an answering tip supervisory relay All :lor controlling the circuit for the answering supervisory lamp AL. Relay AS also acts as a test relay for controlling the connection of the operators elephone set "OT of the talking conductors of the cord circuit E. A link disconnect relay LD is also associated with the answering end and provides the cord circuit E with instantaneous disconnect and recall. Associated with the calling end of the cord circuit E is a callingtip supervisory relay CT and a calling sleeve supervisory relay US for controlling the circuit of the calling lamp CL. 'Tlihe calling sleeve relay CS also controls the disconnection of theoperators set 01 from talking conductors of the cord circuit E. A. party line ringingliey R ri'isprogenerators G,

of the'starting circuit so that no 11 vided for connecting one of a plurality oi i, (l and G with the common *ringing conductor GR L and for controlling the ringing cont ol relay BC. The ringing control relay RC controls the ringing interrupter relay Ill, which through the med imin =01 the constantly rotating interrup'ter R1 apljlies ringingcurrent to the common conductor Gilli to the line of the called subscriber. Associated with the cord ircuit is a service meter device comprising a meter magnet MM having meter control relay Mill. i' issociated with the operators set GT is also a revertive tone relay RTE and a tone device Tl). To the right of Fig. 2, Part 2, show a called substation C similar to the calling substation A and terminating in a line circuit L which comprises the line relay llrll, cut-otl relay CO, multiple jacks ll contactsti, 7, 8 and 9.

Assuming new that the subscriber at the substation A wishes to initiate a call, upon the removal cat the receiver thereat a circuit is closed through the line relay LR including the two sides of the suhscrihens line circuit, in series, and one suhscribefs substation instrun'ient. The line relay LE- upon energ iication places ground upon the start- :ing conductor V and a ground upon the eomn'mn multiple test contacts (3, corresponding to the calling suhscrihers line in the bank of the tinder switches having access to the calling suhscrihers line. The placing of ground upon the starting conductor SlV closes an energizing circuit for th* rotary 'n'iagnct RM of the first tinder switch FS of the series of finder switches associated with the cal-ling suhscrihers line over a circuit traced from battery, through the resistance 333, through the rotary magnet RM, normal contact 15 of the ethnormal contacts ON, starting conductor SW to ground at alternate contact 1'? or line re ay LR. Rotary magnet RM upon energizing steps the switch shaft and wipers 2, 3, i and 5 into engagement with the first set of bank contacts 6, 7, 8 and of the tinder switch FE?) and moves the oil-normal contacts ON to their alternate position. The movement of the elf-normal contacts ON shifts the normally closed cont: ct 15 to its alternate position, which closure of alternate contact l5 closes a local substitute circuit for the magnet RM over a circuit extending from battery through the resisiance B, through the winding of magnet its interrupter contact 1 alternate contact 15 of oil-normal contacts tlh norn ".1 contact 18 of the starting relay {5G to ground at normal contact 19 of the test relay 'lll thereby making the movement oi": the

shaft and wipers f2, 3, 4iand 5 int the callingsubscriber should immediately re the line relay LR associated with the calling subscriber it, closes an energizing circuit for the test relay TR traced from ground at alternate Contact 20 ot line relay LR,

contact (3, wiper 2, normal contact 22 ot' the relay St}, inalie-betorc-break contact 21 oi relr'" ll, through the upper winding of the testrelay Til, which winding is of low resistance, through the resistance R to battery. 'i to enerpi'zsingg' circuit through the upper winding oil the relay TR places a shunt around. the windingol the rotary i'nagnet lilll, due to the low resistance path through the said upper wind' 1 pretenting; further actuation of the ,aid rotary magnet Elli, which now remains at norn'ial and prevents further movement of the swit ch wipers I -land 5. Upon the cue 2,,- tion oi relay 'l l'l an energizing circuit for the relay 11 of the finder switch F5 is established, traced from battery through the winding; of the relay ll, alternate contact 323 oi? relay ll li, normal contact 24: of relay ECU, wiper 5, contact 5), through the calling substation A and back through contact 8, wiper l, normal contact of relay 5560 to around at alternate contact 19 of relay TR. A further result due to the cnergiza- 1.. .2 FEW?) V 1 1 J! Lion o l ielay Lin is the closing or a cueuit tor the multiple line lamps Ll; over a path extending from battery, through the multiple lino lamps LL at the ditierent positions of the switchh-tnird, normal contact 2b of relay t' tjtl. to ground at alternate contact '37 of relay TR, thereby displaying a signal bc'l'ore each oi the operators which have acto the multiple answering iacl zs All. further result, due to the energization of relay TR is the closing; of a circuit through the starting); relay 0G and cut-oil relay C0 of the subscribefs line circuit in series over a path extending from battery, through the lower windingof the relay St alteri e Contact 28 of relay TR, wiper 3, contact T and throiugh the ciiit-oll relay Ct.) to ground.

Again referring: to the encrgization of the relay ll, this relay upon energizing closes a substitute locking circuit for the relay TR independent of its original energizing circuit, over a path extending; from battery through the resistance R, through the upper winding of the relay TR, alternate maltebe'fore-brealr contact 21 of relay 11 to ground through the lower winding of relay TR, thereby making the energization of the relay TR dependent upon the relay 1.1. The relay it} upon energization closes a locking circuit for itself traced from battery, through its upper winding, its alternate contact 30 to ground at alternate contact 3( or" the cit-normal contacts ON. The relay St} upon energizing also extends the starting; wire gil through its alternate contact 33 to the next tinder switch and the opening of its r-ormal contact 22 opens the test circuit, which extends from the wiper 2. The energization of the cut-oil relay C0 of the subscribers line circuit opens the energizing circuit of the line relay LR, thereby re- .iuoving ground from the starting conductor Bil and from the bank contact (3 at contacts 17 and 20, respectively. The ground is removed from the starting conductor p /JV before the relay St has connected the starting conductor SW through to the neat linder switch, due to the contact S3 of the relay St} being so adjusted that the alternate contact 1i" oi? relay LR is opened beit'oro contact- 33 oi the relay S8 is closed.

Referring again to Fig. 2, assuming that the switches FEB, 1 53, etc., are at normal and a subscriber in the group a is initiating a call, this action brings about the closure of alternate contact 17 of its associated line rclay to bring; about the energization of the motor magnet RM of its associated finder switch IFS, contact 15 of oil-normal contacts ON, through its motor magnet RM to battery. The magnet steps the wipers of switch t?) into engagement with contacts of the calling; line. Likewise, when a subscriber in the group 7) initiates a call, the motor mag} net of the groups associated switch FS is energized to select the contacts of the calling line. initiation of a call in group 0 by a subscriber brings about the cnergization of its associated line relay which will start its associated tinder switch FS to select the contacts of the calling line. The initiation of a call in group (Z by a subscriber brings about the energization of its associated line relay, which will start its associated tinder switch F5 to select the contacts of the calling line, and the initiation of a call in group c by a subscriber brings about the starting of its associate tinder switch F8 to select the contacts of the calling line, thus providing a means for starting a selector or the entire group of selectors at one time, follows:

Assuming lines 1-, 14, 24, 34 i and 44lall call at the same instant, selectors FS, Fl", ITS, F5 F53 all start simultaneously and. select the calling lines, and by referring to Fig. 1 it will be noted that the switches FS, FS, etc., will move four steps into engagement with the contacts l, 14, 24-, 34 and M, as the groups a, Z), 0, d and e are associated with the first ten contacts of each switch FS, FS', etc.

Assuming that two calls are initiated in the contacts of the ca over tlllg 'u'i eti i v tothe motor mag net ct t' witch F55 and the magnet steps the into orig-z agement 'withthe caning line. Upon engagementof the wipers with "ling line-an energizing circuit for the relay tit} is brought'about, as previously described, and the closingot its alternate contact' ileu ends the soartingconductor tilV to the switch The second call, which originates in the group a, upon the closing of the alternate contact 17 of its associated line relay, will'extend ground through the said a-lternate'contact 17 over the starting conductor Sly, tl'irou'gh alternate contact 33 of the relay 8;: of switch l l ,i l I X '1'- Fl}, over the starting conductdr SW through the 'iiorn'aally closed contacts 15 of the elf-normal con acts ON, through the motor magnet oi the switch F8 to battery. The n'iotor magnet of switch F5 now steps the wipers oi the said switch into en age ment with the contacts of the second calling line and when the wipers of the switch Fl) engage the contacts of said calling line, an energizing circuit for the relay S6 of is trot-@111; about as previously switch FEB V descril'ied, and extends the starting conductor Edll through the now closed contact 33 of the relay 3G to the next finder sw tch of the 'oup, which is the tinder swi'tch F53 should a third subscriber of group a. inin'iediately initiate a call, the ground will be extended from the alternate contact l? of its associated line relay LR through ahteruate contacts and 33 of relay SG, tilt? of switches ITS, FS through normal contact 15 of oil-normal contact ON of switch liS' (assuming it is idle), through its *iated motor magnet to battery. The now actuated -to step its wipers tch ES is into ene'ai einent with the contacts of the iup; subscriber oi the group a, and reng to liig. 1 the wipers of the switch Flin are stepped to group (H, which contains the contacts of the a group of lines which are lines 1 to 10.

Should a subscriber of the group b initiate a call, the subscribeifs line relay extends iround over the starting wire S y V to the motor magnet of its associated finder normally closed swi'tcl'i i s, through the contact 15 of cit-normal contacts ON of switch 735%. The motor n'iagnet will step the u'i 'iers into engagement with the contacts calling line and when in engagement 1. 4. or die therewith the relay SQ of the switch FS' we as previously described, and exls the starting conductor SW through its alternate contact 33 to the neat idle switch. I

lining that the three subscribers in "cup '4 have called and are still conas above described, should a second slibscribeir of the group b initiate a call, the operation ot'the subscifxer s lated line relay connects ground over the stai-un conduotonSlV through alternate contact 33"o't relay 556: of switch FE), alternate contact 33 ot' relay St} of switch aiternate'contact oi. relay SG of switch F5 alternate Contact 38 oi? relay SG of switch F3 to the switch F55 which we are assuming is idle. The ground extending over the startiiig conductor from the second calling subscriber'of the group 5 how extends through normal cohtact 15 of olt-normal contacts 0N of the switch F53 through its motor magnet to battery. The motor magnet new steps the wipers into engagement with contacts of the second calling line of the group Z) and as 'rou) Z) which contains lines 11 to 20, is the group 6? 0t theswitch F8 the said wipers are stepped over thirty sets of contacts. U10l1 the thirty-first step of the wipers of the switch F8 they are placed in engagement with the first contact s'et associated with the group of lines containing lines 11 to 20. From the foregoing it may be seen that any line calling may use any tinder switch dependin ag upon the idle or busy condition of said switches, and that the time interval between the number of calls'coining in at the same instant has been materially reduced.

It will be seen that by slipping the bank multiple of the six switches according to my invention, the amount of work to be performed by the finder switches is minimized; that is to say, the tinder switches are not compelled to move to the full limit of their range of adjustmentas is often true of the usual multiple arrangement employed prior to my invention. In other words, each finder switch is enabled to perform the work imposed upon it without necessarily operating the full range 01 its switch adjustment as is often true of such switches when the contacts or terminals thereof are multipled together in the old way. The wear and tear on the switches is materially reduced to a rninih'nfni. It will also be seen that by this arrzingeniient of slipping the harm multiple t the switches, as previously described, all possibility of the burden of the work being placed upon some one particular switch, thus distributing the work throughout the different switches, regardless of whether the calls are all coining from one particular group of subscribers or more or less evenly from the subscribers throughout the entire group of any lines.

Again "referring to the description of Fig. 3, parts 1 and 2, and assuming that the finder switch 1 S does not find a grounded bank contact 6, due to the fact that the calling subscriber has replaced his receiver and removed the round from the bank contact Lil switch has advanced to the said grounded bank contact, in a case of this kind the finder switch FS will advance step by step to its fully operated position, in which position a circuit will be closed through the upper winding of relay TR over a path extending from battery through resistance B, through the upper winding 01 the relay TR, make-before-break contact 21 of relay 11, normal contact 22 of relay SG, wiper 2, and the last contact 6 of the bank, which is grounded. Relay TR operating causes the energization of the relays SG and 11, as before described, the only difference being that in this instance the relay SG energizes over a path extending to the last contact of the bank of contact 7, over which the wiper 3 passes, this last contact being permanently connected to ground. "lelay 55G locks up, as before described, but the relay 11 does not remain energized, as before, due to the fact that its substitute circuit is opened at the calling subscribers switchhook. The relay 11 (lie-energizing opens the locking circuit of the relay TR, due to the "fact that contact 22 of relay SC has opened, permitting the said relay TR to tie-energize. Relay TR deenergizing closes a circuit for release magnet RE over a path extending from battery through the winding of the said release magnet RE, alternate contact 18 of relay SG to ground at normal contact 19 of relay TR. The release magnet RE upon energization moves the retaining pawl from the ratchet, thereby permitting the switch shaft and wipers to restore to normal under spring tension. The-release magnet RE is held energized as long as relay SG is held in its ener ized position, and the relay SG is held energized until alternate contact 31 of offnormal contacts ON is returned to its normal position. The oft-normal contacts ON are restored to normal when the switch shaft assumes its normal position, thus placing the apparatus in condition to be used for other calls.

Returning now to the point when the finder switch FS was operated to select the subscriber at the calling substation A and to light the multiple line lamps LL at the different operators positions, an idle operator noting the glowing of the line lamp LL before her inserts an answering plug AP of the cord circuit E into one of the multiple jacks AJ. The insertion of the plug AP in multiple jack AJ closes a series energizing circuit for the answering sleeve supervisory relay AS of the cord circuit E and the relay SCO of the finder switch FS; said circuit extending from battery through the windings of the relay AS, in series, normal contact 10 of the link disconnect relay LD, sleeve contacts of the connected plug AP and jack Ad to ground through the winding of the relay SCO. The relay AS energizing closes, providing that the cord circuit E is the first cord circuit to be connected to the jacks AJ, a shunt about the upper high resistance winding at its alternate contact 102, there placing the low resistance winding of said relay AS in series with the relay 5C0 of the finder switch F53. The low resistance winding of the relay AS creates a low resistance path and prevents a relay AS or' another cord circuit from operatively energizing and connecting its associated operators telephone set in circuit with the calling subscribers line. The relay SCO of the finder switch FS upon energization connects the talking conductors of the finder switch FS through its alternate contacts 24 and 25 to the tip and ring contacts of the jack AJ and the opening of its normal contact 26 opens the circuit of the multiple line lamps LL, and the closing of its alternate contact ll closes a substitute circuit for the relay 11 over a circuit extending from battery, through the winding of relay 11, alternate contact 23 of relay TR to ground at alternate contact ll of relay 860. This substitute circuit oi relay 11 of the finder switch FS is independent of the original energizing circuit of relay 11, which included the calling substation.

Returning now to the cord circuit E, a

further result due to the energization of the supervisory relay AS is the bridging of the answering tip supervisory relay Al across the subscribers talking circuit, the circuit of the relay AT extending from battery through the upper winding of the said relay A l, normal contact 4-2 oi? the link disconnect relay LD, ring contacts of the connected plug AP and jack AS, alternate contact 2% of relay SCQ, wiper 5, contact 9, through the calling substation A, back through contact S, wiper 4-, alternate contact of" relay SCO, tip contacts of the connected plug Al and jack Ail, normal contact 443 of the relay LD, alternate contact 414io'li relay Aid to ground through the lower winding of relay A The relay AT upon energization opens its normal contact 4:5 to prevent a pren'iature lighting of the answering supervisory lamp AL and also to prevent a premature operation of the link disconnect relay Ll). The closing oi: alternate contact 4th of relay Al closes a circuit for the meter relay Mil, from battery through the winding of the meter relay MR, alternate contact -16 of re lay All to ground at normal contact 4-? or the calling sleeve supervisory relay CS. The meter relay MR upon energize n actuates the meter magnet MM to operate the registering apparatus.

A further result due to the energization of the relay AS is the bridging of the opts ators telephone set OT across the talking conductors of the cord circuit E, tl' gh alternate contacts 48, 49 of the said relay AS,

over conductors 50, 51 through normal conlihltS 5Q, 53 of relay CS, conductors 54, 55 to the talking conductors of the cord circuit E. The operator is now connected to the talking conductors oi the cord circuit; E, thus being placed in connection with the calling sul scriber at the substation A and now inquires the Wants of the said ca lling subscriber.

Assuming that it is the subscriber at the substation G that is vi 'anted, the operator tests the line of the called subscriber at c, to its idle or busy condition, and it the said line is idle she then inserts the calling plug; Cl into a jack J connected the line circuit l/ ot the called substation C.

lit the line oi the called substation C is busy, the touching oi? the tip plug Ct to the sleeve oi the jack J will close a circuit 'l'rom the busy or battery potential upon the sleeve of the jack J to the tip of the plug Cl contact of relay Bl, through contact 58 ot the sleeve supervisory relay CS and through the tertiary winding oi the operators induction coil and condenser to ground, thus giving the operator a busy cliclr in her head receiver and notifying her of the busy condition of the called line. The operator tnereupon notifies the calling subscriber that the called subscribei."s line is busy.

5; that the called subscriber at c is a subscriber whose substation is connected to a part ,'--line o't which the calling suo scriber is a party, the touching or the sleeve multiple :aclr J of the calling sul'iscr berfs line by the calling plug GP closes a circuit from battery or busy potential found upon the sleeve oi. the n'iultiple jack J through the tip oi the plug GP, contact 57 of relay El to contact 58 of relay CS, through the revertiw tone relay ll'llt to ground. The relay ltlll upon energizing closes a circuit from the tone device TD to alternate contact 60 oi relay lt'lfll through contact 61 of the answering sleeve supervisory relay AS, the normal contact 62 ot the calling sleeve siuiiervisory relay US, through normal contact 1-0 of? the link disconnect relay Ll), the sleeve oil the plug AP and the sleeve oi the multiple jack Ad, through the condenser (33 and through alternate contact oi" he iy Tit of the tinder switch FF), Wiper 3, the engaged contact 7, thence through the sleeve of lhe jac J, which is be g engaged by the t p of the calling plug; through the tip oi the plug); 3?, contact or oil the relay ill, through contact or: the re ay CS, through the tertiary winding of the operators indue tion coil, througli the condenser 59to ground, thereby giving the operator a rerertire tone test from the tone diwice TD. lhe operator then notifies the calling si'ibscrib-er the substation A to replace his receiver upon the switchhook for a moment so that thcalledsubsoriher may be signaled, as will be more fully hereinafter described.

Assuming that the line of the called subscriber at substation C is idle, the insertion of the calling plug GP into the jack J of the called subscribers line closes a series energizing circuit for the calling SltBGVG SUPGIVlSOiy relay CS and cut-oil relay GU over a path traced from battery through the Winding of the said relay CS, the sleeve contacts of the connected plug GP and jack J to ground through the winding 01 the cut-off relay CO. The relay CO upon energizing disconnects the line relay LR from the line circuit of the called subscriber. The calling sleeve supervisory relay upon energization disconnects th operators set OT from the talking conductors of the cord circuit E at its contacts 52 and 53', and the opening of its normal contact 58 opens the circuit 01 the revertive test relay RTE, and the closing of its alternate contact 47 closes a circuit for the ailing supervisory lamp CL traced from battery through the said lamp, normal contact6t of ringing control relay RC, normal contact 65 of link disconnect relay LD, normal contact 66 of the calling tip supervisory relay CT to ground at the alternate contact 47 of relay CS. The circuit of meter relay MB is also opened when the normal contact l? of the relay CS assumes its alternate position, and the meter relay MR de-energizingnopens the circuit of the meter magnet li/lld, allowing the same to deenergize. The operator next depresses one of the ringing hey plunger-e of the ringing key RBI to connect one of the ringing generators G, G, G G to the common ringing conductor GEL and to initiate the operation of the automatic ringing equipment, The operation of the end spring 68 of the ringing key BK When a key plunger is de pressed closes a circuit for the interrupter relay RI, extending from battery, through the upper Winding" of said relay RI, momentarily closed and spring contact 68, nor n'ial contact 65 ot the linl: disconnect relay LD, normal contact 66 to the calling tip supervisory relay CT and alternate contact 1-? of the calling sleeve supervisory relay CS to ground. The relay RI upon energizing connects the selected generator, Which We will assume is the generator G, to the common ringing conductor GEL, the circuit being traced 'lroin the ungrounded pole oi the generator G, through alternate contact (39 of the depressed ringing hey plunger, over common ringing conductor GEL, alternate contact 57 of relay El, tip contacts of the connected plug GP and jack J, through the call bell at the called substation '0, back through the ring contacts of the'connected plug GP and jack J to ground at alternate contact of relay RI, and this passage of ringing current the instant a plunger is depressed assures a preliminary ring of the call bell at the called substation the instant that the ringing key BK is operated.

A further result due to the energization of the relay Eli is the connection of an audible ringing tone to the calling subscribers line, through the alternate contact 71 of relay R1, to indicate to the calling subscriber that the call bell at the called substation is being operated.

A further result, due to the energization ot the relay R1, is the closure of an energizing circuit for the ringing control relay RC extending from battery through the winding of the relay til, alternate contact 72 of relay El, normal contact 65 of the link disconnect relay LD, normal contact 66 ot the relay CT to ground at alternate contact d7 of relay CS. The relay RC upon energization closes a locking circuit for itself, traced from battery through the winding ot the said relay RC, its alternate contact (i l, normal contact 65 of relay Ll), normal contact 66 of relay CT to ground at alternate contact d7 of relay CS. The relay RC upon energization opens its normal contact (B lto open the circuit of the calling supervisory lamp CL, and the closure of its alternate contact 75 connects the constantly rotating interrupter I in circuit with the ringing interrupter relay R1, the circuit being traced from battery through the lower winding ot the relay RI, through alternate contact 75 of relay RC, through the interrupter l to ground. The ringing relay RI is thus intermittently energized and deenergized to connect ringing current over the previously described path to operate the call bell at the called subscribers substation C.

Upon the response of the called subscriber at the called substation C, a circuit is closed through the called tip supervisory relay CT, traced from battery through the lower winding of the said relay, normal contact 70 of ringing interrupter relay RI when the said relay BI is in one of its tie-energized positions, through the ring contacts of the connected plug GP and jack J, through the now closed contacts oi the substation switchhook, back 'hrough the tip contacts of the connected jack J and plug OP, normal contact 57 of relay RI, alternate contact 58 of relay US to ground through the upper winding of relay CT. The relay CT upon energization opens the locking circuit of the ringing control relay R0 at its normal contact 66, thereby preventing further applications ot ringing current to the called subscribers line. The relay RC de-energizing closes the talking conductor strands at its normal. contacts 76 and 77, through to the called subscriber at the called substation (l, and the opening of alternate contact 75 disconnects the interrupter I from the ringing interrupter relay RI. The subscribers at the calling substation A and called substation (1 are now in conversational circuit and said talking circuit may now be traced over the heavily marked conductors.

Assuming new that the conversation has terminated, the subscriber at the substation A upon replacing his receiver upon its switchhook opens the energizing circuit of the answering tip supervisory relay AT. The relay AT upon de-energizing closes an energizing circuit for the link disconnect relay Ll) at its normal contact lf), said circu't being traced from battery through the winding ot the said relay Ll), normal contact 45 of relay AT, alternate contact 78 of relay AS to ground at alternate contact l? of the calling sleeve supervisory relay CS. The relay Ll) upon energization opens the series energizing circuit for the relay AS or the cord circuit E and relay $00 of: the tinder switch FS at its normal contact 40, and closes a substitute energizing circuit of the answering sleeve supervisory relay AS extending from battery through the lower winding of the relay AS, alternate contact 162 out the relay AS, alternate contact 40 of relay Ll), alternate contact 78 ct relay AH to ground at alternate contact 4'"? of relay CS. The relay AT de-energizing closes a circuit tor the answering supervisory lamp All, traced ttroni battery throi'lgh the said lamp AL, normal contact 45 of relay AT. alternate contact 78 of relay All to ground at alternate contact 47 of relay CS.

A further result due to the energization of the link disconnect relay Ll) is the opening of its normal contacts as and 4:3 discern necting the tip and ring conductors of the cord circuit E from the tip and ring conductors ot the jacks All, thereby operatively disassociating the calling subscriber's line and the tinder switch F8 from the link circuit E. The relay SCO of the finder switch FS Clo-energizing opens the energizing circuit of the relay 11 at its alternate contact ll, which relay upon de-energizin opens the energizing circuit of the relay TR at its alternate make-betore-break contact 21, permitting the said relay TR to tie-energize. The relay TB upon its de-energization closes an energizing circuit for the release magnet RE over a path extending from battery through the winding of the said release magnet RE, alternate contact 18 of relay SG to ground at normal contact 19 of relay TR. The release magnet RE upon energization moves the retaining pawl from engagement with the switch shaft ratchet, thereby permitting the shaft and wipers 2, 3, 4iand 5 to restore to normal.

The called subscriber C upon replacing his receiver upon the switchhook opensthe circuit oil the calling tip supervisory relay GT at the substation switchhook contacts. The relay CT upon restoration closes a circuit for the calling supervisory lamp CL, the said circuit being traced from battery through the said lamp CL, through alternate contact of relay Ll), normal contact 66 of relay CT to ground at alternate contact 47 of relay CS. The operator noting the glowing of the answering supervisory lamp All and the calling supervisory lamp CL removes the answering plug AP from the jack AJ and the calling plug Cl from the jack J which opens the series energizing circuit of the calling sleeve supervisory r lay CS and cut-oft relay CO 01 line circuit L associated with the called substation C. The relay CS upon de-energization opens its alternate contact 47, allowing the link disconnect relay L1) to deenergize. The answering supervisory relay AS also deenergizes and brings about the etiacement of the supervisory lamps CL and All. The relays LD and AS upon de-energization restore the apparatus of cord circuit E to normal, rendering it available for connecting other subscribers lines.

Should the calling subscriber at the sub station A desire to recall before the answering plug AP is removed from the jack AJ, he may do so. The subscriber upon removing his receiver for a recall again energizes the line relay LR, thereby grounding the common starting wire SW and starting another finder switch FS or the same finder switch of such recalling subscribers line. As soon as the finder switch finds the contacts of the calling subscribers line the connection is completed the same as before described. If the finder switch is started which was used in the previous connection, the finder switch FS upon finding the calling subscribers line will again cause the multiple line lamps LL to glow, and either the same operator or another operator may seize the call.

In working out my invention, I have employed preferred circuit arrangements and also a certain number of switches for handling the calls from a particular number 01 lines. I do not wish to be limited to the exact circuit arrangement as shown or the number of switches specified, but aim to cover all such changes and modifications as come within the spirit and scope of the appended claims.

What I claim as new and desire to secure by United States Letters Patent, is:

1. A telephone system including a major group of lines divided into sub-groups of lines, an automatic switch having a set of wipers operable in but one plane associated with each of said sub-groups, an auxiliary automatic switch associated with said switches, means whereby it a connection is desired with one of the lines in one of said subgroups its associated switch is operated to etiect such connection, and if a second connection is desired with a second line in the said subgroup said auxiliary switch is operated to effect the connection. I

:2. A telephone system including a major group of lines divided into sub-groups of l s, an automatic switch associated with each or said sub-groups having a single set of contact wipers operable in a single plane, an auxiliary automatic switch associated with said switches having a single set 01 contact wipers operable in one plane only, means whereby it a connection is desired with a line in one of said sub-groups its associated switch is operated to effect such connection, and if a second connection is desired with a line in the same sub-group the switch associated with a second sub-group is operated to effect such connection, said auxiliary switch having its bank contacts so connected that it first has access to the lines of one sub-group and then to lines of the other sub-groups.

3. A telephone system including lines divided into sub-groups, a switch associated with each sub-group having access to all the lines of the different sub-groups through its single set of wipers which have motion in one plane only, an auxiliary switch, circuit connections whereby the switch associated with the first sub-group first has access to the lines oi its sub-group, and circuit con nections whereby it said switch is busy the auxiliary switch is operated, said auxiliary switch also first having access to the lines of said sub-group through its single set of wipers.

at. A telephone system including lines divided into sub-groups a, b and 0, a switch associated with each of said sub-groups, an auxiliary switch, the banks of the switch associated with subgroup a being so arranged that it first has access to the lines of subgroup a, then to the lines of sub-group b, and then to the lines of sub-group 0, the switch associated with sub-group of lines b first having access to the lines of sub-group b, then to the lines of sub-group c and then to the lines oi sub-group a, and the bank of the auxiliary switch being so connected that it first has access to the lines of sub-group a,

then to the lines of sub-group Z) and then to the lines of sub-group c.

5. A telephone system including a group of lines divided into sub-groups, a plurality of automatic switches each having access to the said groups of lines said switches being provided with but a single set of contact wipers and operable in one direction only, the bank contacts of said switches being so connected that one switch first has access to the lines of one sub-group and then to the lines of the other sub-groups through its said wipers, the second switch being so connected that it first has access to the lines of a different sub-group and then to the lines of the other sub-groups through its said wipers, etc, and an auxiliary switch associated with said first switches having its bank contacts so connected that it first has access to the tin-es 01 one sub-group and then to the lines of the other sub-groups.

Signed by me at Chicago, in the county of Cook and State of Illinois, this 12th day of April 1920.

GEORGE E. EATON. 

